Manuel Pellegrini has denied Manchester City have surrendered a championship-winning advantage, insisting Liverpool could drop points to allow his team to again take charge of the title race.

Towards the end of March City were three points behind the leaders, Chelsea, with two matches in hand. But after drawing 1-1 at Arsenal on 29 March and losing 3-2 to Liverpool on Sunday, Pellegrini's side know that even if both extra games are won they will still be a point behind the Merseyside club.

Asked if City have surrendered a strong advantage in their bid for a second title in three seasons, the manager said: "No, the opportunity we lost [means that now] we don't depend on what we can do, of course. But it was a tough game against Liverpool in their own stadium.

"We didn't deserve to lose that game but things happen. We continue with the same trust and we'll do it till the end of the season. We still have two games in hand and we hope we can win those six points. We must play very well especially [against Sunderland]."

While Gus Poyet's side are at the Etihad Stadium on Wednesday evening, Pellegrini is convinced Liverpool and Chelsea, who are five points ahead, having played two matches more, are still capable of slipping up. "You have the whole season and maybe all the teams lost some games away, [so far] Liverpool against Hull or Chelsea against Crystal Palace, all the teams will drop points in unexpected games," he said. "The season is very close for all the teams. When we finish on 11 May we analyse what happened with the games. But for now we are fighting with the same chances as the other teams.

"Of course it is possible Liverpool can drop points, or Chelsea, or our team also. Any team can drop points every week. In the Premier League all the games are close and it's not easy to go and win."

Pellegrini has suffered the serious blow of losing Yaya Touré for up to a fortnight because of a muscle injury. That means the Ivorian, whose 18 goals make him the Premier League's third highest goalscorer, behind only Luis Suárez and Sergio Agüero, may miss at least three of City's final six matches in the league.

"Yaya has a muscle injury. We will see with the doctor how many days," said the manager. "Maybe it is not so [bad] as we thought at the beginning, but I think he needs at least 10 days or two weeks to recover."

Vincent Kompany, who was at fault for two of Liverpool's goals, including Philippe Coutinho's 78th-minute winner, entered the match as a concern due to a knee injury. But he and Agüero, who came on as a 68th-minute substitute following a hamstring problem, are available for Sunderland's visit.

"Kompany is OK, fit [for tomorrow], he is on the squad list. Sergio also," said Pellegrini, who stuck by his decision to choose Kompany. "He started the game because he is the captain, he made all the proof before the game, he said he was OK and the doctor said that, so I don't regret that."

Sunderland put up a decent fight when the sides met in the Capital One Cup final last month and despite their subsequent loss of form, Pellegrini said he was still wary of them. "I think it is very dangerous, the position that they are in the table – more dangerous than a match that was one month ago. Sunderland are in a very bad position and they know they have to win so they will be very dangerous."